class_docstr: Support SAM for semantic segmentation.
  Refer to https://huggingface.co/docs/transformers/main/model_doc/sam
code: def label_key(self):
      return f"{self.prefix}_{LABEL}"
  
imports: import logging
  import os
  import time
  import warnings
  from typing import Dict, List, Optional, Tuple
  import torch
  import torch.nn.functional
  from omegaconf import DictConfig
  from torch import nn
  from transformers import SamConfig, SamModel
  from transformers.models.sam.modeling_sam import SamImageSegmentationOutput
  from ..constants import CLASS_LABEL, CLASS_LOGITS, COLUMN, IMAGE, IMAGE_VALID_NUM, LABEL, LOGITS, MASK_LABEL
  from .utils import assign_layer_ids, freeze_model_layers
label_desc: Use image node_id 6 for calling the SAMForSemanticSegmentation obj's underlying member method code with example usage: obj.label_key() and returns: self, str, LABEL